File fasteners of the type set out in this specification have a central body portion and a prong extending from each end of the body portion, each prong being narrower than the body portion. File fasteners of this type are conventionally produced using eccentric punch presses.
It has become practice to attach the central body portion of the fastener to a folder. The body portion is usually either mechanically attached to the folder or adhered to the folder. One example of mechanical attachment occurs via lugs which extend from the body portion into openings defined in the folder. In one example of when the body portion is adhered to the folder, a prong is received through each of a pair of openings defined in a length of adhesive tape. This particular method of attachment is described in U.S. Pat. No. 5,059,051 (Corey).
The prongs of fasteners which are attached to folders are usually coated with a suitable material such as paint. The purpose of this is to protect a user from being cut and to inhibit oxidation of the prongs.
The inventor has communicated with and visited leading manufacturers of file fasteners all over the world. The inventor has familiarized himself with the technology of a number of these file fastener manufacturers.
Egidius Jansen of The Netherlands, is the leading manufacturer of file fasteners in Europe. Egidius Jansen manufactures file fasteners from either tin plated material which is pre-plated or pre-lacquered. The fasteners are then blanked from such pre-plated or pre-lacquered material. This leaves the edges and the tips of the fastener exposed.
The inventor believes that VanGuard Tool & Die of Milwaukee, Wis., U.S.A., is the leading manufacturer in the U.S.A. of the "lug"-type fasteners described above.
VanGuard's operation is relatively sophisticated. It employs high speed punch presses, carbide dies and the latest technology and equipment available. VanGuard's operation is also highly automated with conveyorized automatic removal of scrap from the premises. VanGuard uses pre-coated coil for the manufacture of the file fasteners. VanGuard's fasteners are blanked from the precoated coil. The edges and the tips of the fasteners are thus also exposed. PA1 Grip Binders' is the largest manufacturer of file fasteners in South Africa and their operation is also a relatively sophisticated one using high speed presses and carbide dies. At present, Grip Binders, as with Ideal Stampings, only manufactures tin-plated fasteners. The fasteners are manufactured from preplated stock, leaving the edges and tips of such fasteners unplated. PA1 Charles Leonard and Company of Glendale, N.Y., U.S.A. manufactures coated fasteners. These fasteners are manufactured from pre-coated material. Thus, the edges and tips of the fasteners remain exposed. PA1 forming the body portion and the prongs; and PA1 applying a protective coating to substantially the entire side surfaces of the prongs and their tips.
Ideal Stampings of Philadelphia, Pa., U.S.A., manufactures tin-plated file fasteners. These fasteners are inserted into file folders by end users. Ideal Stampings does not manufacture a coated fastener. It follows that edges and tips of these fasteners remain exposed after blanking.
A problem which has arisen during the manufacture of file fasteners is that the blank perimeter of a file fastener can be burred. This results from the blanking process. This problem has to some extent been overcome by a striking operation known as "spanking" the burr which is done in an additional stage in the die. This striking operation is designed to flatten the burr.
This method has been partially successful. However, a residual burr often remains as the die becomes blunt and requires removal of the die for sharpening. Thus, a substantial number of burred fasteners can move through the production process without being detected.
The fasteners are coated in an attempt to solve this problem. However, when the fasteners are blanked from pre-coated material, the edges and the tips remain unprotected as a result of the blanking process. Until now, it has not been possible for manufacturers to obtain a commercially viable solution to this problem.
Oxidation of uncoated edges can occur. This oxidation in combination with a burr can result in a dangerous cut to the fingers of an end user. The fasteners are a high volume product and hundreds of millions are manufactured and used in the United States annually. Moreover, users are required to bend the prongs into an upright, vertical position to accept the papers to be filed. The prongs must then be bent back into a horizontal position. It will be appreciated that users' fingers are in direct contact with the edges and the tips of such prongs frequently and continuously.
Further, when the fasteners are used in combination with compressor bars it is necessary to fold the prongs inwards over the compressor bar. A locking member is then slid across the prongs to secure the prongs in position. This results in a movement of fingers across the prongs. Any residual burr on the prong edges can thus cut a user's fingers.
It is clear that, although some progress has been made in preventing injury due to uncoated edges and tips, a commercially viable method of coating the edges and the tips of fasteners to prevent injury altogether has not been achieved to date.
A further problem associated with uncoated edges and tips is that edges of punched holes in paper are damaged by such uncoated edges and tips. This problem is common knowledge to users of files and file fasteners.
An attempt to solve this problem has been the use of self-adhesive reinforcing rings. However, the attachment of such reinforcing rings constitutes an additional cost. Further, the use of such rings is regarded as a nuisance or burden and, as a result, the rings are not used in the majority of cases. The reinforcing rings also result in the need for extra filing space.
Up until the present invention, the problems of having uncoated edges and tips as set out above have been regarded as insoluble. Prior to the invention, the most efficient and economically viable method of manufacturing fasteners of the type having a central body portion of greater width than the prongs was to blank the fasteners out of a sheet of metal in a single stroke. Such fasteners are typically manufactured at speeds of between three hundred and six hundred fasteners per minute.
The conventional methods of coating finished products entails the preforming or blanking of the product, and the coating of the product thereafter, in order to cover all sides of the product. This involves individually handling the product after blanking or forming in order to coat all sides. It will be appreciated that should the file fasteners be coated in this manner, the cost of manufacturing the file fastener would render the file fastener commercially uncompetitive. In order to be commercially viable, file fasteners sell for between US$0.01 and US$0.017 each (ex-factory). This price could not be achieved if the file fasteners were individually handled for coating after they were formed.
In order to coat the fasteners separately, the fasteners must be collected, oriented correctly, and held in a jig or holding device, in order to be coated. It follows that a portion of each fastener must necessarily be covered over by the holding device, resulting in an uncoated portion or patch corresponding to the holding area.
A disadvantage of such separate coating is that it would rule out roller coating the fasteners.
The most significant disadvantage of holding the individual fasteners, is that the handling would drive the cost of coating up to a price which would be substantially more than the cost of the fastener itself. As a result, the fastener would be commercially uncompetitive.
The inventor believes that this invention provides a method whereby a file fastener of the type described above and having prongs with coated edges and tips can be manufactured in a commercially viable manner.